diagnosing network speed bottlenecks

[Shawn O'Shea]

>
> Speed tests like http://www.dslreports.com/speedtest?flash=1 report my
> performance as...
> 4,909 Kb/s Download
> 3,055 Kb/s Upload
>
> But, in my experience downloading files, I rarely get anything like
> that.   In fact, while the DSL Reports Speed Test is checking my
> system, I'm watching the "Network History" graph on the "Resources"
> tab of System Monitor (v2.26.0.1) aka gnome-system-monitor and it's
> not breaking 800Kbps.  I then used wget to download MySQL Workbench
> and it reports 33,373,104 downloaded in ~42 seconds at a rate of 783
> KB/s
>
>
Please note that you need to be very careful in reporting these numbers.
Bandwidth is generally reported in Kbps (or Mbps) (little 'b') meaning
kilobits per second, meaning 10^3 bits per second.

Downloads are normally measured in KB/s (or MB/s) (big 'B') meaning
kilobytes per second where there are 1024 bytes (aka 2^10) bytes in a
kilobyte.

So your download averaged 783 KB/s * 1024 bytes/KB = 801,792 bytes/s

There are 8 bits in a byte so 801,792 * 8 = 6,414,336 bits/s or bps so
that's 6.414 Kbps or 6.4Mbps

I have the same Comcast plan and get similar results. I ran this from my
living room over 802.11g (54Mbps) on my Ubuntu laptop.

DSLreports speed test to Speakeasy in NY reports 5,209 Kbps. I downloaded
the linux kernel source from Pair's mirror (Pair has a lot of bandwidth) (
http://kernel.mirrors.pair.com/pub/linux/kernel/v2.6/linux-2.6.30.tar.gz)
with wget which reported that the 60MB file came down at an average 595 KB/s

595*1024 = 609280 * 8 = 4,874,280 = 4,874 Kbps vs DSLreports 5,209 Kbps is
pretty close.

-Shawn
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